Research Of Closed Silo Stored Grain In The Natural Convection And The Coupled Heat And Moisture Transfer

The grain is hygroscopic porous medium, with moisture absorption and moisture absorption characteristics. General grain after harvest, most of the time in a closed non-natural storage ventilation condition. In view of the seasonal and diumal variation of granary and climatic conditions, temperature and humidity will make the grain heap changes occurred in the cycle, resulting in over the storage security index. This paper will take the grain storage in local coupled heat and moisture transfer process as the research object, numerical simulation software of multi-physics field(COMSOL)by means of numerical simulation, research on approximate dynamic changes in winter and summer conditions of grain temperature and humidity, give full consideration to the storage of grain as a hygroscopic porous media with complex heat, moisture source. At the same time due to the storage of grain itself has had vital signs, which itself must consume organic matter in the warehousing period, through respiration heat, producing wet.Under natural storage conditions, a temperature gradient is generated inside the grain bulk resulting in the changes in the outside world under climatic conditions, and then natural convection is formed in the barn, grain heap internal moisture migration and redistribution is caused by this airflow organization, the end result is to increase the moisture in the grain pile partial, the moisture exceed the safe water storage, causing moldy food.This article explores the change of temperature field and moisture field with time in the approximate conditions during summer and winter seasons in the natural conditions through theoretical analysis and numerical simulation. Through the different starting points this research discusses the above problem, including the comparison of the different seasons of hot and cold food core,the comparison of the different temperature difference in the initial season with the same wet-based food, the comparison of the different initial wet basis in the same temperature difference and the same season food, the comparison of the temperature field and moisture field considering the food respiration. Through theoretical analysis of simulation results, this paper is of great significance for the grain storage technology development and food industry management.